1. Field of Invention
The present invention generally relates to keyboards for mobile devices. More particularly, the present invention relates to a universal mobile keyboard including an infrared interface and an energy-efficient keyboard scanning method.
2. Discussion of the Related Art
Personal digital assistants (PDAs) have become more popular and affordable with improved technology, allowing for enhanced display quality, color richness, contrast, processing speed, power efficiency, memory capacity, RF communication capability, and other desirable characteristics. Similar advances are also made in other mobile devices, such as cellular phones, smart phones (PDA plus cellular handset), industrial data terminals, and tablet PCs. Thus, there is a growing need for an efficient and convenient universal device and method for data entry and for providing a user interface with these mobile devices.
Some mobile devices offer touch-sensitive LCD screens with built-in recognition software for data input by handwriting or “graffiti.” However, data input using graffiti is not convenient or efficient unless the user is properly trained in the method. Even then, data input using graffiti is not usually as fast as using a keyboard.
Some PDAs have built-in soft or virtual keyboards, or other input means, such as thumb-boards, silk-screen keyboards, and rubber keyboards. However, these input means are less efficient than small foldable keyboards that connect to the mobile device, such as a PDA, and offer the familiar desktop/notebook keyboard input style.
Such small foldable keyboards typically require a connector customized for each mobile device make or model. Usually a device-specific connector is used for both data exchange and for holding the mobile device in place. Such a connector often lacks stability. Also, when a user gets a new mobile device, the user would also need to purchase a new keyboard. Some keyboards provide changeable connector heads. However, these changeable connector heads achieve only limited flexibility, given the many connector types that are used among mobile devices.
Accordingly, wireless keyboards (e.g., infrared-based keyboards) are desired. However, typical infrared (IR)-based keyboards in the prior art suffer from several disadvantages. For example, a typical prior art IR keyboard uses a polished metal reflector to guide the IR beam from the keyboard to the IR port of a mobile device, which can be found at the top or at the side of the mobile device. Such a polished metal reflector is awkward to adjust and difficult to keep steady. Furthermore, to achieve the IR beam reflection, a stronger IR beam intensity than otherwise needed for data transmission is used. Thus, battery energy is inefficiently used, resulting in a shorter battery life or requiring a larger number of batteries (e.g., from 1 to 3 AAA batteries) or a higher battery capacity. In addition, a stronger than required IR beam intensity may also in some instances overwhelm or “blind” the IR receiver circuitry in a mobile device IR port, causing data error or a sluggish response. A reflector-based IR beam guidance scheme has limited flexibility in aligning to IR ports, as the IR port may be found in any of a variety of possible locations on a mobile device.
Therefore, what is needed is a keyboard for a mobile device that is operable with a large number of mobile devices. In particular, a keyboard with an IR interface is needed that is operable with and adjustable for a variety of possible IR port locations found on various mobile devices. Additionally, a keyboard scanning method is needed that is highly energy efficient to increase battery life and improve keyboard portability.